Apparatus for conveying sheets

ABSTRACT

An apparatus for conveying sheets comprising first sheet feed means including a pair of rollers forming a nip therebetween, and second sheet feed means also comprising a pair of rollers forming a nip therebetween. A sheet is fed through the first sheet feed means while maintaining the second sheet feed means at rest, and immediately after the leading end of the sheet has reached the second sheet feed means, the latter is momentarily operated to cause the leading end of the sheet to be bitten into the nip of the second sheet feed means, whereafter the latter is deactuated. A loop of the sheet is formed between the first and second sheet feed means as the sheet is continuously fed through the first sheet feed means. When the loop has grown to a given size, the second sheet feed means is set in operation continuously until the sheet is fed therethrough for delivery of the sheet.

United States Patent Hirafuji APPARATUS FOR CONVEYING SHEETS [75] Inventor: Van Hirafuji, Yokohama, Japan [73] Assignee: Ricoh C0,, Ltd., Tokyo, Japan I [22] Filed: Oct. 19, 1973 [211 Appl. No.: 407,833

[30] Foreign Application Priority Data Oct. 25, 1972 Japan 47-10684] [52] US. Cl 271/265, 271/80, 271/270, 271/272 [51] Int. Cl B65h 5/06, B65h 29/20 [58] Field of Search 271/264, 265, 266, 270,

[56] References Cited UNITED STATES PATENTS 3,062,537 11/1962 Hanstein et al 271/80 X 3,241,831 3/1966 Axlid 271/265 X 3,410,551 11/1968 Tiger et al. 271/172 [451 Feb. 4, 1975 Primary Examiner-Evon C. Blunk Assistant ExaminerBruce H. Stoner, Jr.

Attorney, Agent, or FirmCooper, Dunham, Clark, Griffin & Moran [57] ABSTRACT An apparatus for conveying sheets comprising first sheet feed means including a pair of rollers forming a nip therebetween, and second sheet feed means also comprising a pair of rollers forming a nip therebetween. A sheet is fed through the first sheet feed means while maintaining the second sheet feed means at rest, and immediately after the leading end of the sheet has reached the second sheet feed means, the

latter is momentarily operated to cause the leading end of the sheet to be bitten into the nip of the second sheet feed means, whereafter the latter is deactuated. A loop of the sheet-is formed between the first and second sheet feed means as the sheet is continuously fed through the first sheet feed means. When the loop has grown to a given size, the second sheet feed means is set in operation'continuously until the sheet is fed therethrough for delivery of the sheet.

8 Claims, 9 Drawing Figures PATENTED FEB 4 I975 sum 2 or 3' PATENIED FEB 41975 SHEET 30F 3 F |G.6(b)

M 6 G F APPARATUS FOR CONVEYING SHEETS BACKGROUND OF THE INVENTION The invention relates to an apparatus for conveying sheets, and more particularly to such apparatus in which the leading end of a sheet being conveyed is momentarily stopped.

When a sheet is fed through a first sheet processing system at a relatively low speed and is then fed through a second sheet processing system at a greater speed, the sheet delivered from the first system can not be directly fed into the second system, because the differential speeds in the respective systems may cause an undue tension in the sheet. For example, when a picture is transmitted. in a facsimile system and is recorded on an electrostatic recording paper, the recording paper can not be directly fed into a developing system for the purpose of developing the image recorded, since the recording paper will be fed intermittently or at a low rate within the recording system while a developing roller included in the developing system will be continuously run at a relatively high speed.

SUMMARY OF THE INVENTION Therefore, it is an object of the invention to provide an apparatus for conveying sheets in a smooth manner between a pair of systems having different sheet processing speeds such as anelectrostatic latent image recording system and a developing system therefor.

It is another object of the invention to provide useful control means for second sheet feed means included in the apparatus of the invention.

In accordance with the invention, there is provided an apparatus for conveying sheets comprising first sheet feed means for feeding a sheet at a first speed equal to a sheet processing speed within a first system with which the apparatus is associated, second sheet feed means for feeding the sheet at a second speed equal to a sheet processing speed within a second system with which the apparatus is associated, and control means for maintaining the second sheet feed means inoperative until the leading end of the sheet fed by the first sheet feedmeans reaches the second sheet feed means and for momentarily operating the second sheet feed means, concurrently with or immediately after the sheet has reached the second sheetfeed means, for a short period of time sufficient to cause the leading end of the sheet to be bitten into the second sheet feed means and for thereafter disabling the second sheet feed means, said sheet being continuously fed by the first sheet feed means into the span between the first and second sheet feed means to form a loop in the sheet therebetween, said control means being operative, when the loop in the sheet has grown to a given size, to operate the second sheet feed means until the sheet moves past therethrough. In view of such an arrangement, a smooth sheet conveying operation is assured when the sheet processing speed within the second system is more or less higher than the sheet processing speed within the first system, or when the first system and the first sheet feed means are intermittently driven. Because the leading end of the sheet is bitten into the second sheet feed means when a loop of the sheet is formed between the first and second sheet feed means, the resilience in the sheet iseffective to prevent the disengagement of the leading end of the sheet from the second sheet feed means, thereby assuredly allowing a loop of a sufficient size to be formed.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 3 are schematic views of the apparatus for conveying sheets according to the invention, illustrating a sheet which is conveyed through two pairs of rollers having different feed rates;

FIG. 4 is a perspective view of an exemplary momentary stop device for the leading end of the sheet used in the apparatus for conveying sheets according to the invention;

FIG. 5 is a cross section of the spring clutch provided at one end of the sheet feed roller; I

FIGS. 6 (a) to (c) are schematic views illustrating the operational relationship between the select member and the operating lever which constitute together a control means; and

FIG. 7 is a front view of another example of the momentary stop device for the leading end of the sheet which may be used in the apparatus of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. I, there are shown a first pair of feed rollers l, 2 rotating in the respective directions indicated'by arrows at a relatively low speed for conveying a-sheet 3, such as one delivered from a facsimile recording system 30, for example, toward a developing system 40. On the discharge side of the first pair of rollers are disposed a second pair of feed rollers 5, 6which normally remain stationary'A pair of guide plates 7, 8 extend intermediate these pairs of rollers. The rollers 5, 6 of the second pair are'shown fixedly mounted on shafts I] and 12, the shaft 12 being a drive shaft and connected with the other shaft 11 through a gearing, not shown. When a clutch to be described later is operated, the drive shaft 12 is driven for rotation in the direction indicated by an arrow 73. A detection switch 10 is provided to detect the time when the sheet 3 reaches the second pair of rollers 5, 6, and another detection switch 20 is located so as to detect the time when the trailing end of the sheet 3 reaches in the vicinity of the first pair of rollers 1, 2'.

As shown in FIG. 5, a spring clutch 13 is mounted on one end of the drive shaft 12, and comprises a sprocket l4, spring 15 and drum 16. This end of the drive shaft 12 is stepped to have reduced diameters. The boss 14a of the sprocket 14 is rotatably mounted on that portion of the shaft 12 which has the least diameter 12a, and the spring 15 is tightly wound around the periphery of the sprocket as well as that portion of the shaft 12 which has an intermediate diameter 12b. One end of the spring is secured to one end of the drum 16. As shown in FIG. 4, the drum 16 is formed with a stepped notch 17 into which legs 18a, 19a at the free end of operating levers 18, 19 are disposed. The leg 18a bears against the lateral edge 17a of the notch 17, while a gap 21 is defined between the leg 19a and the lateral edge 17a. The sprocket 14 is normally maintained rotating in the direction indicated by an arrow 24 by a chain 23 which extends there-around and is moving in the direction indicated by an arrow 22. This rotative effort ordinarily would be transmitted to the shaft 12 through the spring 15 which is stressed to engage the surfaces of boss 14a and intermediate diameter 12b but because the operating lever 18 prevents the rotation of the drum 16 to which one end of the spring 15 is secured, the spring is held in a slightly unwound condition so that intermediate diameter 12b, boss 14a, and the spring 15 remain free relative to each other, whereby the drive is not transmitted to the shaft 12.

Referring to FIG. 4, both operating levers 18'and 19 are rotatably mounted on a shaft indicated by an axis 25 which is mounted on a stationary member (not shown), and are connected at their one end with springs 26 and 27, respectively, the other end of which is secured to a stationary point, whereby the levers are urged in a direction to abut against the drum 16 with their legs 18a, 19a. An integral folded piece 19b provided on the upper edge of the operating lever 19 extends over the upper edge of the operating lever 18 to cause a rotation of the operating lever 18 in the direction indicated by an arrow 28 when the operating lever 19 is rotated in this direction by an action to be described later.

Abutting against the upper edge of the operating lever 18 in a direction perpendicular thereto is the end of an operating arm 31a of a select member 31, the base of which is pivotally connected with a shaft 32 which is in turn pivotally connected with U-shaped limbs 33a, 33b extending from the opposite edges of a slide member 33. A torsion spring 34 is disposed around the shaft 32 and its respective ends abut against the slide member 33 and the select member 31, respectively, urging an inclined arm 31b of the select member 31 into abutmentwith the upper edge of the operating lever 18. The slide member 33 is formed with a pair of elongate slots 35 and 36, into which are loosely fitted a pair of stationary pins 37 and 38, respectively. A tension spring 39 has its one end secured to a stationary point and its other end secured to the slide member for urging the latter to move upwardly. However, such movement is limited by the engagement of the pins 37 and 38 with the lower end of the respective elongate slots 35 and 36, respectively. A solenoid 41 is disposed below the slide member 33 and has its plunger 41a connected with the lower end of the slide member 33 through a spring 42. Y

Returning to FIG. 1, when thesheet 3 is fed by the first pair of rollers 1, 2 to the right and it leading end reaches the nip between the rollers and 6 of the second pair which remain stationary at this time, an operating rod a is moved angularly as shown in FIG. 2 to actuate the detection switch 10. Upon actuation of the switch 10, the solenoid 41 shown in FIG. 4 is momentarily operated to cause one reciprocatory stroke of the slide member 33. However, it is to be noted that the switch is preset so that it is operated immediately before the leading end of the sheet actually reaches the nip between the second pair of rollers, and that the second pair of feed rollers are driven to rotate at a higher speed than that of the first pair of feed rollers. For these reasons, there is a definite time delay until the second pair of feed rollers are rotated after the switch 10 has been operated. in this manner, it is assured that the sheet is positively held bitten between the rollers without inducing an undue tension in the sheet. While not shown in the drawings, such a time delay can be readily achieved by connecting any known delay. unit such'as a delayed acting relay between the switch 10 and the solenoid 41. Where the first pair of feed rollers are driven intermittently by means such as a step motor 2a, the drive pulses for the step motor or the angle of rota- .tion of the step motor may be counted to drive the'solenoid 41 when a predetermined number of pulses have been detected. In this instance, the switch 10 can be eliminated. During such reciprocatory motion, as the slide member 33 moves downward, the operating arm 31a of the select member 31 presses against the operating lever 18, whereby the latter rotates in the direction indicated by the arrow 28 about the shaft 25. As a result of such rotation, the leg 18a of the operating lever 18 is disengaged from the notch 17, whereby the drum 16 rotates in the direction indicated by an arrow 124 on account of the drive imparted thereto. This rotation takes place for a small angle until the leg 19a of the other operating lever 19 'abuts against the lateral edge 17a of the notch. The net effect of the momentary operation of the clutch 13 is that the second pair of feed rollers 5 and 6 are rotated in the directions indicated by arrows for a small angle, biting the leading end of the sheet in between them.

Referring to F1G.'6, the operating arm31u lect member 31 initially assumes the position shown in FIG. 6 (a), and moves to the position shown in FIG. 6 (b) upon momentary operation of the solenoid 41. As the operating lever 18 rotates, its leg 18a is freed from notch 21 and then rides on the peripheral surface of the rotating drum 16, so that the operating lever 18 remains in an inclined .position. When the slide member 33 returns to its original position from the down position, the select member 31 rotates under the resilience of the spring 34, and its operating arm 31a moves into alignment with the upper edge of the operating lever 19 as shown in FIG. 6 (c).

After theleading end of the sheet 3 has reached the nip between the second pair of feed rollers, the continued feeding operation of the first pair of feed rollers 1 and 2 serves form a loop 30 as shown in FIGS. 2 and 3. 1f the leading end of the sheet 3 has not been held between the rollers of the second pair, there is a risk of the leading end of the sheet becoming deflected from the nip between the second pair of rollers 5 and.6 when the loop 3a has grown to a large size. The purpose of the'momentary operation of the clutch 13 is to remove such disadvantage by causingthe leading end of the sheet to be bitten between the rollers 5 and.6 of the second pair as illustrated in FIG. 3.

As the sheet 3 is further conveyed through the first pair of feed rollers 1 and 2 and its trailing end is detected by the operating rod 20a of the detection switch 20, the solenoid 41 is operated for an increased period of time. The operation of the solenoid 41 causesthe select member 31 to rotate the operating lever 19 in the direction of the arrow 28, thereby disengaging the leg 19a of the lever 19 from the notch 17 to release the drum 16 from the constraint. Thus, the clutch 13 becomes active again to transmit the drive from the normally rotating sprocket to the shaft 12 and the second pair of feed rollers 5 and 6, whereby the sheet 3 is conveyed in the direction of an arrow 4 at a relatively high speed. While there is a speed differential between the first pair of feed rollers l, 2 and the second pair of feed rollers 5, 6, the presence of the loop 3a of the sheet 3 is effective to prevent the sheet 3 from being tensioned as a result of such speed differential between the both pairs of rollers. When the operating lever 19 is operated, the fold piece 19b thereon presses against the adjacent operating lever 18, so that the legs 18a and 19a of both levers l8 and 19 are removed from the periphof the seeral surface of the drum 16, thereby avoiding interference with the rotation of the drum 16.

The energization of the solenoid 41 is interrupted by a returning motion of the operating rod a when the trailing end of the sheet 3 is delivered from the second pair of feed rollers 5, 6, or by a control over the period of time during which the solenoid 41 is energized, thereby causing the legs 18a, 19a of both operating levers to again bear against the peripheral surface of the rotating drum l6 and to drop into the notch 17 as it rotates to a position opposite them, thereby returning to the original condition shown in FIG. 4. When the operating lever 18 returns to its original position, its upper edge abuts against and slides along the inclined arm 31b of the select member 31, thereby bringing the operating arm 31a into alignment with the upper edge of the operating lever 18. lt will be appreciated that instead of detecting the position of the trailing end of the sheet in order to determine the time at which the solenoid 41 is to be energized for the second time, such time may be determined by a further detection switch 44 shown in HO. 3 which is operated when the loop 3a has grown to a given size.

FIG. 7 shows another embodiment of the invention in which the drum 16 having a notch 17 (see FIG. 4) is replaced by a notched member 51 having a plurality of notches 51a around its periphery. The notched member 51 may be mounted on the drum 16 with notch 17 eliminated. Referring to FIG. 7, a detent lever 52 has a tab 520 which is adapted to be received in any one of the notches in the notched member 51 to prevent the rotation of the drum 16. One end of the detent lever 52 is pivotally mounted on a pivot 53 which is stationary and is connected'with a spring 54 having its other end secured to a stationary point, the spring urging the detent lever 52 so as to cause the tab 52a to bear against the notched member 51. A release solenoid 55 has its plunger 55a connected with the detent lever 52 through a spring 56. The free end 52b of the detent lever 52 bears against the periphery of a gear 58 which is rotatably mounted on a stationary shaft 57. The periphery of the gear 58 is also engaged by the free end 59a of an operating pawl 59 which is pivotally mounted at a pivot 61 on a slide member 62. The operating pawl 59 is urged to rotate counter-clockwise by a spring 63 which is secured to the member 62 at one end and to the operating pawl 59 at the other end. The slide member 62 is formed with a pair of spaced elongate slots 62a and 62b in which are fitted stationary pins 64 and 65, respectively, and is urged upward by a tension spring 65 connected thereto, the other end of the spring 65 being secured to a stationary point. At its lower end, the slide member 62 is formed with a folded piece 62c which is connected with the plunger 66a of a release solenoid 66 through a spring 67. The solenoid 66 is used to provide a momentary release of the detent lever 62, while the solenoid 55 is used to release the lever 52 for an increased period of time.

Referring to FIG. 1, as the leading end of the sheet 3 reaches the second pair of feed rollers 5 and 6 to operate the switch 10, the solenoid 66 shown in FIG. 7 is momentarily operated after a definite time delay as mentioned previously, to cause one reciprocatory stroke of the slide member 62. In response to such reciprocatory motion, the gear 58 is rotated counterclockwise to raise the free end 52b of the detent lever, thereby disengaging the tab 52a from the notched member 51 and releasing the latter. The release of the notched member 51 continues for a short period of time during which the member 51' rotates in the direction indicated by an arrow 24. This permits the clutch 5 13 (refer FIG. 5) to be actuated for a short period of time to rotate the second pair of feed rollers 5 and 6 in order to bite the leading end of the sheet therebetween as shown in FIG. 2. When the loop 3a in the sheet 3 has grown to a sufficient size to operate the switch 44, or to operate the detection switch with its trailing end. the solenoid 55 is energized, causing the detent lever 52 to be rotated clockwise. The interval during which the solenoid 55 is energized or the period of time during which the notched member 51 is released is relatively long to cause the sheet 3 to be conveyed through the second pair of feed rollers 5 and 6 to a developing system 40 (FIG. 1), for example. The release signal for the solenoid 55 may be provided by a returning movement of the operating rod 10a of the switch 10 or by a separate detection switch which is operated when the trailing end of the sheet 3 has moved past the second pair of feed rollers 5 and 6.

What is claimed is:

1. An apparatus for conveying sheets comprising:

a. first sheet feed means for feeding a sheet at a first speed;

b. second sheet feed means for receiving said sheet from said first sheet feed means and feeding the sheet at a second speed which is greater than the sheet feeding speed of the first sheet feed means; and

c. control means for maintaining the second sheet feed means inoperativeuntil the leading end of the sheet fed by the first sheet feed means reaches the second sheet feed means, and momentarily operating the second sheet feed means for a short period of time when the leading end of the sheet has reached the second sheet feed means, and for operating the second sheet feed means at the second speed when a loop formed in the sheet between the first and second sheet feed means has grown to a given size subsequent to the termination of the momentary operation of the second sheet feed means.

2. An apparatus according to claim 1 in which each of the first and second sheet feed means comprises a pair of rollers abutting against each other.

3. An apparatus according to claim 2 further comprising means for driving the pair of rollers which constitute the first sheet feed means in intermittent rotating motion with a small incremental angle of rotation.

4. An apparatus according to claim 1 in which the control means comprises:

d. clutch means for operating said second sheet feed means:

e. a resiliently pivotable first lever for operating said clutch means upon pivoting to permit a sheet feeding operation by the second sheet feed means when the leading end of the sheet fed by the first feed means reaches the second sheet feed means;

f. a resiliently pivotable second lever for interrupting the operation of said clutch means and the second sheet feed means shortly after said sheet feeding operation is permitted and for subsequently pivot- 65 ing to'operate said clutch means; and

g. operator means including a solenoid for pivoting the first and second levers to render said clutch means operative and for releasing the first and secnd levers to render said clutch means inoperative.

5. An apparatus according to claim 4 in which said solenoid is operated in response to a signal from a microswitch which detects the leading end of the sheet fed by the first sheet feed means reaching the second sheet feed means.

6. An apparatus according to claim 1 in which the control means comprises a rotating member releasably connected to the second sheet feed means and having a plurality of notches along its peripheral surface, a detent lever for engaging a notch in the rotating member for preventing the rotation of the rotating member, a member for disengaging the detent lever from a notch in the rotating member for a short period of time to cause a momentary rotation of the rotating member, and a solenoid for maintaining the detent lever disengaged from a notch in the rotating member to permit a continued rotation of the rotating member,

7. An apparatus according to claim 6 in which the member for disengaging the detent lever from a notch in the rotating member for a short period of time is operative when the leading end of the sheet has reached the second sheet feed means, and said solenoid is operative when a loop formed in the sheet between the first and second sheet feed means has grown to a given size,

8. An apparatus according to claim 1 in which the size of the loop formed in the sheet between the first and second sheet feed means is detected by a microswitch disposed in the space in which the loop of the sheet is formed, said microswitch being operated by the sheet as it forms a loop of a gradually increasing size. 

1. An apparatus for conveying sheets comprising: a. first sheet feed means for feeding a sheet at a first speed; b. second sheet feed means for receiving said sheet from said first sheet feed means and feeding the sheet at a second speed which is greater than the sheet feeding speed of the first sheet feed means; and c. control means for maintaining the second sheet feed means inoperative until the leading end of the sheet fed by the first sheet feed means reaches the second sheet feed means, and momentarily operating the second sheet feed means for a short period of time when the leading end of the sheet has reached the second sheet feed means, and for operating the second sheet feed means at the second speed when a loop formed in the sheet between the first and second sheet feed means has grown to a given size subsequent to the termination of the momentary operation of the second sheet feed means.
 2. An apparatus according to claim 1 in which each of the first and second sheet feed means comprises a pair of rollers abutting against each other.
 3. An apparatus according to claim 2 further comprising means for driving the pair of rollers which constitute the first sheet feed means in intermittent rotating motion with a small incremental angle of rotation.
 4. An apparatus according to claim 1 in which the control means comprises: d. clutch means for operating said second sheet feed means: e. a resiliently pivotable first lever for operating said clutch means upon pivoting to permit a sheet feeding operation by the second sheet feed means when the leading end of the sheet fed by the first feed means reaches the second sheet feed means; f. a resiliently pivotable second lever for interrupting the operation of said clutch means and the second sheet feed means shortly after said sheet feeding operation is permitted and for subsequently pivoting to operate said clutch means; and g. operator means including a solenoid for pivoting the first and second levers to render said clutch means operative and for releasing the first and second levers to render said clutch means inoperative.
 5. An apparatus according to claim 4 in which said solenoid is operated in response to a signal from a microswitch which detects the leading end of the sheet fed by the first sheet feed means reaching the second sheet feed means.
 6. An apparatus according to claim 1 in which the control means comprises a rotating member releasably connected to the second sheet feed means and having a plurality of notches along its peripheral surface, a detent lever for engaging a notch in the rotating member for preventing the rotation of the rotating member, a member for disengaging the detent lever from a notch in the rotating member for a short period of time to cause a momentary rotation of the rotating member, and a solenoid for maintaining the detent lever disengaged from a notch in the rotating member to permit a continued rotation of the rotating member.
 7. An apparatus according to claim 6 in which the member for disengaging the detent lever from a notch in the rotating member for a short period of time is operative when the leading end of the sheet has reached the second sheet feed means, and said solenoid is operative when a loop formed in the sheet between the first and second sheet feed means has grown to a given size.
 8. An apparatus according to claim 1 in which the size of the loop formed in the sheet between the first and second sheet feed means is detected by a microswitch disposed in the space in which the loop of the sheet is formed, said microswitch being operateD by the sheet as it forms a loop of a gradually increasing size. 